At the same time that the paving industry is experiencing the commercial stresses of increasingly strict environmental controls of all kinds, the paved surfaces themselves are experiencing the stresses of greater traffic and larger, heavier vehicles as well as increasing corrosion from the ever-wider use of chemicals for snow and ice removal. The competing demands of new laws and performance standards virtually mandate improvements in paving materials and maintenance methods therefor.
One way to maintain the integrity of paved surfaces is actively to preserve them, so as to avoid the necessity of rebuilding or resurfacing them. A bituminous pavement rejuvenator for such a purpose is disclosed in U.S. Pat. No. 3,221,615, incorporated herein by reference, which is a coal tar derivative composition containing specific ingredients and having particular specifications. Other pavement treating compositions are disclosed in U.S. Pat. Nos. 3,261,269 and 4,661,378, also incorporated herein by reference, which disclose pavement dressing conditioners which contain the above-described bituminous pavement rejuvenator together with additional ingredients and/or solvents. These pavement treating compositions are generally spread or sprayed onto existing pavement surfaces (not only bituminous surfaces but concrete and other surfaces as well) to preserve and to restore the integrity of the pavement.
Even these pavement preserving and restoring compositions, however, do not meet all the needs of the current pavement maintenance industry. For example, pavement restorers often wish to restore the original black color of bituminous pavement which has faded to gray or white. This change of color to black is needed for safety reasons to preserve contrast between painted center and shoulder lines; even intact road markings become faint or invisible when the road surface itself fades to white or gray. It has also been discovered that blacker pavements retain more heat from solar energy, and thus need fewer and less frequent applications of de-icing chemicals than faded roads do. Those who pave and maintain road surfaces, and are thus always mindful of the need to minimize costs and damage associated with de-icing chemicals, therefore also appreciate the need for restoring a dark or black color to paved surfaces of all kinds.
Even beyond these concerns, a ubiquitous goal in restoring old asphalt is inevitably the solving of the "water run-off" problem. The same drying, sun bleaching and oxidation of the asphalt material which originally caused the fading color also invariably causes the asphalt surface to harden, lump and crack. This loss of smooth surface causes rainwater to pool and/or to run in large and sometimes deep gulleys which wreak havoc on traffic and further the degradation of the road. Restoration of the original, smooth, waterproof surface is thus an important consideration in any pavement preservation technique.
Accordingly, a need remains for a treating composition and method for asphalt and other bituminous pavement materials which can simultaneously permanently blacken it and smooth and waterproof it to overcome unwanted water run-off.